So long, spirulina? Knotted kelp adds nutrients, reduces salt & removes artificial flavours

By Niamh Michail

- Last updated on GMT

© Seaweed & Co
© Seaweed & Co

Related tags Seaweed knotted kelp Salt reduction Umami Health claim spirulina

UK firm Seaweed & Co's wild harvested knotted kelp (Ascophyllum) beats spirulina for iodine, potassium, calcium and magnesium, and can reduce salt in packaged foods or replace artificial smoke flavours, it says.

The company, which harvests its seaweed from the Scottish islands of the Outer Hebrides, says its seaweed is the first to be “DNA authenticated​” with independent DNA analysis to ensure traceability, and has a proprietary, patent-pending drying and milling process that, according to independent analyses by a UKAS-accredited laboratory, results in higher levels of antioxidants and polyphenols than other food-grade competitor brands.

Its three B2B bulk ingredients are all made with organic, wild-harvested Ascophyllum, ​also known as rockweed or knotted kelp.

PureSea Natural, a powder with seaweed flavours and umami notes that work well in savoury foods such as baked goods, meats, fish, and sauces with other glutamate-packed ingredients such as cheese and tomato. 


Although it is not salty, its umami-rich profile means it can also be used to reduce the salt content of foods. “We generally advise trialling a like-for-like replacement with salt at 100% replacement, 50/50, and then testing the control with standard salt.  Most success has been around the 50/50 mark,” ​said Dr Craig Rose, founder and managing director of Seaweed & Co.

PureSea Smoke is made by naturally oak smoking seaweed for around 72 hours in a BRC- and Kosher-accredited facility, and the resulting product can be used to replace artificial smoke flavour in various foods. UK retailer M&S used PureSea Smoked in its smoked Hebridean seaweed mayonnaise. 

The third product, PureSea Protect, is microencapsulated using a thin layer of plant protein,  and can be used for beverages, sports nutrition and powder blends to boost the nutritional profile without altering the flavour of the original product.

A member of the common brown algae family, Ascophyllum ​seaweed is high in iodine, which allows manufacturers to make six EU-approved health claims for the support of normal thyroid health, skin, metabolism, cognitive function, nervous system and development in children.

One gram of PureSea seaweed powder contains over twice as much potassium as spirulina (31 mg compared to 14 mg), five times as much calcium as chlorella (15mg compared to 3 mg) and is almost on a par with spinach for magnesium (8 mg for spinach compared to 9 mg in PureSea).

The company has supplied UK food firms such as Premier Foods and Greencore, as well as private label manufacturers for retailers including M&S and Waitrose. 

It also manufactures a range of consumer-facing specialty oils and food supplements​ under the Weed and Wonderful brand.

Contamination concerns

Rose said that microplastics, which have been found in foods as diverse as honey, tap water and sea salt​, are not a concern for seaweed.

The seaweed being harvested off the coast of Scotland. © Seaweed & Co

“It doesn’t absorb during growth as far as we are aware. We are in discussions with our testing labs to explore ways of testing for this to further reassure customers. I have a PhD in marine biology and I founded [the company] with the aim of getting the best quality, sustainable seaweed into people's lives," ​he told FoodNavigator.

“I am passionate about ensuring this is done in a way that conserves and even enhances the marine environment. This is fundamental to me and the ethos of our brands.”

The company did not say how much seaweed it sells in volume but, according to Rose, growth has been “rapid​” in the past couple of years.  “The locations of our harvest and species chosen means that sustainability is not under threat, and we have a highly scalable opportunity into the tens of thousands of tonnes,” ​he added.

Seaweed & Co’s biggest market is the UK but it also has distributors across Europe, the US, South Korea, Israel and Australia.  

Both PureSea Smoke and PureSea Natural are available as a fine powder of less than 400 microns and as medium-sized granules of 0.4 to 1.5 mm, and have a four-year shelf life. PureSea Protect is 100 to 210 microns.

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